International Day Of Immunology 2025: Brain And Immunity

According to Professor Kjesten Wiig, Director of the Malaghan Institute, the future of brain research lies in neuroimmunology. As a trained neuroscientist, she explains how this fast-rising field could transform how we understand neurological disorders like Alzheimer’s, Parkinson’s and motor neuron disease.

Few conditions inspire more dread than the creeping shadow of neurodegenerative disease. At times, it feels almost taboo to talk about, perhaps because it touches on something deeper than physical decline. We fear the loss of our mental faculty because it threatens the very core of who we are; our memories, our relationships, our sense of self. What makes neurodegenerative disease more unsettling is just how little we understand about these diseases and how few tools we have to stop them.

So how can we protect our brains from decline and retain our health for longer? I believe the answer lies in our immune system.

An unseen alliance

The brain is a unique organ, isolated from the rest of the body through the blood-brain barrier, a protective mechanism that separates the brain from the body’s blood supply. The barrier allows essential substances like oxygen and glucose to pass through, but keeps out potentially harmful substances that might lurk in the blood like bacteria and viruses.

The blood-brain barrier keeps the brain stable and safe, but it’s a double-edged sword. The barrier also keeps out many drugs and immune cells needed to fight diseases that occur in the brain. This has made neurological diseases especially difficult to treat and study, as any therapy must first overcome this stubborn hurdle.

For decades, the brain was believed to function outside the reach of the immune system. But that notion is now outdated. There is an unseen alliance between the brain and a few privileged immune cells, and this relationship could hold vital clues to conditions such as Alzheimer’s, Parkinson’s, motor neuron disease and even mental health disorders.

A unique immune environment

The brain’s immune environment is unlike any other found in the body. It is carefully regulated, home to a specialised network of immune cells embedded within a complex web of neurons and glial cells. Chief among these immune cells are microglia, the brain’s resident sentinels. They constantly monitor their surroundings, clear waste and help maintain healthy communication between neurons.

Discoveries such as direct signalling between immune and neural cells have reshaped our understanding of how the brain maintains a healthy balance and responds to injury.

But this balance is delicate. Infections, stress and ageing can offset it, leading to inflammation that gradually erodes brain function.

From the subtle but compounding shifts that come with age, to potential therapies that retrain immune responses, the line between neurological and immune health is becoming increasingly blurred. More and more, these conditions are touching people of all ages and walks of life. While the diseases may differ, from neurodevelopmental disorders in childhood to dementia in later life, the insights emerging from neuroimmunology could hold relevance across this entire spectrum.

An urgent opportunity

At the Malaghan Institute, we believe neuroimmunology is one of the most exciting and urgent areas for research and discovery. With some of the country’s top immunologists and cutting-edge tools at our fingertips, we are uniquely positioned to explore this uncharted territory, forging collaborations with researchers across Aotearoa and globally.

Together, we have the potential to uncover transformative ways of protecting the brain and to offer real hope to those affected by neurological conditions. The need for action is clear, and the opportunity before us is too important to ignore.

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